/**
 */
package com.diudiutechnology.www.yadiudiu.yadiudiu.singlecall.MyActivity;

import android.content.Context;

import java.security.MessageDigest;


public class CheckSumBuilder {
    private static CheckSumBuilder mInstance;
    private Context context;
    private CheckSumBuilder(Context context) {
        this.context = context;
    }
    public static CheckSumBuilder getInstance(Context context) {
        if (mInstance == null) {
            synchronized (CheckSumBuilder.class) {
                if (mInstance == null) {
                    mInstance = new CheckSumBuilder(context.getApplicationContext());

                }
            }
        }
        return mInstance;
    }
	
	public static String getSignature(String appSecret, String nonce, String curTime) {
		return encode("sha1", appSecret + nonce + curTime);
	}
	
	private  static String encode(String algorithm, String value) {
        if (value == null) {
            return null;
        }
        try {
            MessageDigest messageDigest = MessageDigest.getInstance(algorithm);
            messageDigest.update(value.getBytes());
            return getFormattedText(messageDigest.digest());
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
	
    private static String getFormattedText(byte[] bytes) {
        int len = bytes.length;
        StringBuilder buf = new StringBuilder(len * 2);
        for (int j = 0; j < len; j++) {
            buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
            buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
        }
        return buf.toString();
    }
    
    private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

}
